Method and apparatus for providing 3 dimensional image

Provided are a method and an apparatus for providing a three-dimensional image. First projection images are generated by detecting X-rays which are emitted toward an object from different angles. Second projection images about the partial volume of the object are generated by applying front projection and interpolation to the first projection images. The left image and the right image among the second projection images are selected. The selected left image and right image are provided to an observer as three-dimensional projection images.